如何使用 hibernate 生成自定义 ID 而它必须是表的主键 [英] How to generate Custom Id using hibernate while it must be primary key of table

问题描述

这是我的 pojo 课

Here is my pojo class

@Entity

public class Department {


@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)

@Column(name="Department_Id")

private Integer deptId;


@Column(name="Department_Name",unique=true,nullable=false)
private String deptName;


@Column(name="Department_Description")
@NotNull
private String deptDesc;
   //geters and setters

我想要的是 Department_id 必须是这个 Department 表的主键，并且这个键的条目必须是 DEP0001、DEP0002、DEP0003

What i want is that department_id must be primary key of this Department table and entries for this key must be as DEP0001, DEP0002,DEP0003

推荐答案

谢谢大家的回复......最后我在我的 Department 类中做了一些更改，并使用了一个类来生成 ids........这是我的代码

Thank you everyone for your response...... finally i have done some changes in my Department class and used a class for generating ids........Here is my code

@Entity
public class Department {

@Id
@GenericGenerator(name = "sequence_dep_id", strategy = "com.xyz.ids.DepartmentIdGenerator")
@GeneratedValue(generator = "sequence_dep_id")  
@Column(name="Department_Id")
private String deptId;

@Column(name="Department_Name",unique=true,nullable=false)
private String deptName;


@Column(name="Department_Description")
@NotNull
private String deptDesc;

//getters and setters

DepartmentIdGenerator.java

DepartmentIdGenerator.java

package com.xyz.ids;

import java.io.Serializable;
import java.sql.*;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.id.IdentifierGenerator;

public class DepartmentIdGenerator implements IdentifierGenerator{

    @Override
    public Serializable generate(SessionImplementor session, Object object)
            throws HibernateException {

        String prefix = "DEP";
        Connection connection = session.connection();

        try {
            Statement statement=connection.createStatement();

            ResultSet rs=statement.executeQuery("select count(Department_Id) as Id from demo.Department");

            if(rs.next())
            {
                int id=rs.getInt(1)+101;
                String generatedId = prefix + new Integer(id).toString();
                System.out.println("Generated Id: " + generatedId);
                return generatedId;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        return null;
    }

}

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